Lock mandrels can be used to support different flow accessories needed for well control downhole. Typically, the accessory attaches to the lower end of the lock mandrel, and a running tool is located within the lock mandrel from the upper end to run the mandrel and accessory downhole. Then, the lock mandrel with accessory is run-in and set in the well. Once positioned in the well, the running tool is removed, and the lock mandrel anchors and seals the accessory in position in the well's tubing string.
One type of prior art lock mandrel 10 is shown in FIGS. 1A-1B in unlocked and locked conditions. This lock mandrel 10 is commonly referred to as an “Otis X” lock mandrel or standard style lock mandrel with collapsing fishing neck. The lock mandrel 10 is similar to that disclosed in U.S. Pat. No. 4,396,061 to Tamplen et al. As shown, the lock mandrel 10 has a tubular body with a packing element 13 and a retainer sleeve 14 disposed thereon. Locking dogs 20 are carried by the retainer sleeve 14, and a locking sleeve 16 can move on the body 12 within the retainer sleeve 14 between a retracted position (FIG. 1A) and a locked position (FIG. 1B). As in FIG. 1A, a flange 17 on the retracted locking sleeve 16 is moved away from the dogs 20. However, when moved to the locked position (FIG. 1B), the flange 17 expands the dogs 20 outward to engage in a nipple profile.
In use, the lock mandrel 10 is assembled in a run-in condition (FIG. 1A) on a running tool (not shown), and the assembly is run into a well bore on a wireline. The spring 24 biases the locking dogs 20 inwardly so that the dogs remain retracted. Eventually, the locking mandrel 10 lowers below a landing nipple in which it is to be landed. At this point, operators lift the lock mandrel 10 above the landing nipple profile 30 and then lower it again toward the landing nipple. This lowering of the lock mandrel 10 causes the locking sleeve 16 to be moved downwardly to an intermediate position so that the spring 24 urges the locking dogs 20 outwardly against the wall of the flow conductor.
Operators then continue lowering the lock mandrel 10 until the dogs 20 engage the landing nipple profile 30. When engaged, shoulders 22 on the dogs 20 mate with a comparable shoulder 32 on the landing nipple's profile 30. Downward jarring forces then drive the locking sleeve 16 downwardly to the locked position (FIG. 1B). At this point, the locking sleeve 16 supports the dogs 20 in their extended position locked into the landing nipple's profile 30.
Another type of prior art lock mandrel 50 is shown in FIG. 2. This lock mandrel 50 is commonly referred to as a “uniset” lock mandrel and is similar to that disclosed in U.S. Pat. No. 4,883,121 to Zwart. Rather than having a downwardly travelling inner sleeve or mandrel, this type of lock mandrel 50 uses an upwardly travelling inner mandrel 70. As shown, the lock mandrel 50 has the inner mandrel 70 located within a body 60 of the lock mandrel 50. The inner mandrel 70 can move between an upward position (as shown) and a downward position. In the upward position, a flange 72 on the inner mandrel 70 pushes lockout keys 78 outward to engage in a nipple profile (not shown).
In use, a running tool (not shown) holds the inner mandrel 70 down so the lockout keys 78 can retract within the main body 60. When run-in to a setting depth down the tubing string, the lock mandrel 50 stops against a no-go restriction in the tubing. Operators jar downwards to shear pins (not shown) on the setting tool, and fingers 74 on the inner mandrel disengage from a collet on the running tool. This releases the inner mandrel 70 to move upward by the bias of a spring 76, and the fingers 74 move out of a lower groove 62 in the body 60.
At this point, however, the lockout keys 78 are not in line with a profile in a landing nipple so the keys 78 cannot expand until the lock mandrel 50 has been lifted from the no-go. Accordingly, operators lift the lock mandrel 50 from the no-go restriction. When the keys 78 reach the landing nipple's profile, the inner mandrel 70 moves upward by the bias of spring 76 until the fingers 74 reach an upper groove 64. The flange 72 can then hold the expanded keys 78 in the nipple profile to support the lock mandrel 50. Operators then jar upwards on the running tool to shear it free from the set lock mandrel 50.
These two types of lock mandrels 10/50 have been used for many years. Yet, they still do not meet all of the challenges encountered in wells. Unfortunately, the lock mandrel 50 of FIG. 2 requires the use of a no-go restriction downhole to activate the mandrel 50. Using such a restriction may not always be available or preferred in a given implementation. In the lock mandrel 10 of FIGS. 1A-1B, friction from the upward-flowing fluids can push upward against the mandrel's inner components, which may be undesirable. For this reason, various retention features, such as shear pins or snap rings, have been used on this type of lock mandrel 10.
The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.